Overview
Bycatch is the term used to describe animals that are caught unintentionally in a fishery, and discard is the name given to the portion of each catch that is thrown back into the ocean. It is estimated that around 10% of the world’s global catch is discarded at sea each year[1]. Bycatch is a big cause of overfishing, affecting everything from delicate corals to enormous whales.
Definitions
Ghost gear - Ghost nets are fishing nets that have accidentally or purposefully been lost into the natural environment.
Synonyms: Ghost nets, derelict equipment/gear, lost gear/equipment, abandoned nets/gear, discarded equipment, abandoned, lost or otherwise discarded fishing gear (ALDFG).
Deep Dive
Often we hear about plastic pollution and many of us diligently use our reusable bottles, have switched to a bamboo toothbrush and are in the habitat of taking our own reusable bags to the shops. These are all fantastic actions, but one of the leading causes of plastic pollution in the oceans is rarely discussed - plastic pollution from ghost fishing equipment.
Why is fishing equipment lost?
· Snagging on the ocean floor often cut to ensure the safety of the boat
· Conflict with other gear
· Drifting and subsequently lost from where they were deployed
· Theft
· Lack of onshore disposal facilities leading to “dumping” at sea
Why is ghost fishing gear a problem?
Most modern fishing gear is made from plastic, for example, nylon. Plastic is widely used because it’s sturdy, hardwearing and can be made to float easily. These characteristics which make fishing gear incredibly efficient at catching marine life, also enable it to travel long distances in the ocean and remain relatively intact. Over time, plastic fishing gear slowly degrades (break up) into microplastics. Before this happens, however, it can spend many years drifting on ocean currents or entangled in marine habitats and continue to do what they were designed to do - catch and kill marine life.
Fishing equipment is not limited to just nets, fishing lines, floats, cages, sinkers, and storage boxes from commercial fishing, aquaculture or recreational fishing can all potentially end up in the ocean.
Studies from around the globe show that fishing gear often dominates marine debris surveys. And although fishing gear does often appear in higher prevalences near fishing grounds (1) it is also found in remote regions. It is tricky to put a global figure on what percentage of ocean debris is fishing gear, because it varies hugely geographically.
What are the impacts?
According to the FAO (4) pots, traps and gill nets are more likely to “ghost fish” and trawls and longlines are most likely to entangle animals and create greater ecosystem damage. You can find out more about different types of fishing equipment here. Macro plastics are anything larger than 5mm and the effects are often lethal and micro plastics are smaller than 5mm and are normally not lethal but can bioaccumulate and cause stress to marine animals (5) as well as becoming a concern for human health also (6).
The impact of ghost fishing gear is huge, varied and we are still only just learning about the impacts it is having on species and ecosystems. Fishing nets are designed to entrap animals and will continue to catch a whole host of species, whilst adrift in the ocean for hundreds of years due to the durability of plastic. This makes not just the quantity of fishing gear becoming pollution worrying, but impact this gear has long beyond its commercial use. As well as fish, they also entrap many other marine species, often drawn to the caught fish in the netting. They may also assemble juveniles of species that would normally mature in large oceanic seaweed patches for safety, such as turtles. The impact of this in unknown. Entanglement is probably the most well known and well published impact of fishing gear waste. Plastic waste in general kills a million seabirds every year and more than 100,000 marine mammals (7). Putting accurate numbers on the species and numbers of animals killed by ghost nets is extremely difficult because incidents happen at sea where it is unobserved.
This gear can also be consumed accidentally by marine animals. This can cause a number of problems, including fatalities. A recent study (8) showed that organophosphate esters (OPEs) found in Loggerhead Turtle muscles had come from two sources, their food had eaten plastic and it was bioaccumulating and secondly the turtles were eating the plastic themselves showing that plastic is a risk for marine animals in multiple ways.
The Sea Floor
Ghost fishing gear that is designed to sink can cause huge problems for coral reef ecosystems and the seabed. It can physically cause damage when it settles on the reef, with delicate branching corals most at risk of snapping. It can cover and even smother sensitive corals, blocking light and preventing the healthy preening of algae by reef fish. This preening process keeps the corals “clean” and without this maintenance, they can get diseased and increase fatality and the nets themselves can also increase disease in coral systems as they can become stressed by the presence of plastic pollution (9). Unfortunately, we still don’t know much about this process but we’ll learn more as the research continues.
Triggering Negative Feedback Loops
The impact on the reef can be enormous for biodiversity. A healthy reef ecosystem has many parts that work together to maintain biodiversity and health. But it’s not just marine life that is negatively impacted by damage to the reef. Reef ecosystems are nurseries for fish and unfortunately poor fishing practice now, can impact the fishing possibilities of the future. We need healthy reefs for many other reasons too. Healthy reef ecosystems provide ecosystem services, such as storm protection for shore communities. Damage to the reef weakens this defence, and unfortunately sometimes once a negative feedback cycle is started, they can become more susceptible to further damage, perpetuating the negative feedback loop.
Disease Vectors
Ghost nets can provide a suitable vector for some species to travel on (10). Due to their lightweight, sturdy nature- they are able to travel great distances. This has the potential to cause problems for invasive species threat globally. They can also be a vector for pollution accumulation as plastic may also take up persistent toxic substances found in the water and again this is a bioaccumulation risk as marine animals consume this pollution, impacting the health of fish beyond the plastic itself (5).
Social Impacts
There are also cultural, societal and economic. For example, Aboriginal communities living in Northern Australia, that rely on fishing for subsistence and live in remote, cut off areas, ghost nets are a huge burden (11). Not only do they impact food source but they are without areas to recycle or dispose of nets.
Ghost nets can also impact ecotourism. A study in Calofornia found that a reduction of plastic debris on beaches meant an increase in $29.5 million USD aggregate benefits. (12)
They pose safety problems for ocean-going vessels too, as they can also be a navigational hazard.
Resource Intensive Clean Up
Ghost nets can be extremely heavily especially when biofouled and can create a logistical problem to remove. Costs can be huge, one estimate suggests a single net cost $1358 (Canadian Dollar) (13) to remove. This same study also found that it was much more cost-effective to remove the net than let it keep “ghost fishing” in terms of cost on fish stock, without measuring the wider impact on the ecosystem. (**It would be good to add something about the sentience of fish lives but I can’t think how to word this formally**) The process of removing nets, especially from the seafloor is technically difficult too. It usually requires a specialist team of divers who meticulously unpick the nets from the ocean floor or coral reef and send it to the surface with floats.
Beyond Fish Catching Equipment
It’s not just fishing equipment that causes plastic pollution. The whole cycle of fish catch to consumption is hugely plastic intensive. From the polystyrene boxes, wrapping and right to your table. Polystyrene is a particularly worrying plastic as it has health concerns and is not largely recycled due to its low value. Like other plastics, it breaks up into smaller plastics and in the case of polystyrene, it breaks up into very lightweight balls that can very easily float/ get carried in the wind and look a lot like fish eggs.
The role of polystyrene in the fishing industry is actually interesting, as ice packed polystyrene boxes have allowed for bigger catches, as the fish stay fresh for longer meaning fisherman can stay at sea and catch more. They are stored properly and so fish are of higher quality and can achieve higher prices
Hope
Research is currently ongoing to see what can be done to reduce the huge impacts of fishing gear. Simply removing ghost gear from the oceans is not enough, we need to ensure less of it enters the ocean in the first place.
Trials into reusable fish storage boxes are ongoing to reduce polystyrene use and prevent fish waste, but they’ll still allow for huge catches.
Satellite tracking on nets could be a solution, it would reduce net loss- a benefit for fishermen also as nets can cost thousands of pounds. It would also mean lost nets could be traced back to a boat and potentially fined or simply reunited. However, many nets are often attributed to illegal fishing and so will not prevent these losses. Marking of nets has been occurring since the 90’s, but methods often fail and trials for efficient methods are still ongoing. There are currently “Voluntary Guidelines for the Marking of Fishing Gear (VGMFG)" through the FAO (2018) (14)
Could switching back to natural fibres for fishing gear has been suggested as a solution. This would mean the nets degrading if lost, rather than plastic which does not biodegrade. There are a number of problems with this, including practicality for industrial fishing as natural fibres will be heavy, will not last as long, may be more expensive. Also, if these nets are lost, they may still have huge impacts, as they will still take time to degrade.
Natural lines might be more suitable for recreational fishing. Natural lines will degrade faster than nets, whilst still maintaining quality for purpose and not being too heavy for use. Natural lines and proper collection of monofilament lines also important for recreational fishers too. Monofilament lines left in the water can tangle in boat engines potentially very dangerous. Angling societies and tackle shops globally have started setting up fishing line recycling systems to encourage anglers to be more mindful about their wasted line. You can find your nearest line recycling facility here: https://www.anglersnlrs.co.uk/recycling-locations. (15)
Better onshore recycling facilities, both in terms of availability and also recyclability of nets may improve the amount of nets recycled, but dirty nets that have been at sea for many years are harder to recycle still. However, plastic is still an oil based product and divesting from it’s use as much as possible addressing not just the ocean impacts of climate change but also wider global environmental and social justice impacts of oil use. (**Too political?!)
However, the most impactful action most of us can take is reducing how much seafood we eat. Like turning down the tap of the flow of pollution- preventing pollution getting into the system is better than trying to clean up, especially with the nature of global oceans and the far reaching impacts of plastic. So as well as using your reusable bottle, can you take the Fish Free February pledge?
Initiatives
There are a number of initiatives set out to limit the amount of ghost gear entering the ocean and also those working to remove it from the sea and the shorelines.
Aboriginal Conservation Programme in Northern Aus: Tackling ‘ghost nets’: Local solutions to a global issue in northern Australia (link).
Recycle your line: https://www.anglers-nlrs.co.uk/recycling-locations
Global Ghost Gear Initiative: a collaborative effort that brings together governments, NGOs, and the fishing industry to address the issue of ghost gear—a term used to describe abandoned, lost, or discarded fishing gear that continues to trap and kill marine life. The GGGI aims to reduce bycatch by focusing on the retrieval and proper disposal of ghost gear, as well as promoting more sustainable fishing practices. By actively removing this hazardous fishing gear from the ocean, the GGGI not only prevents the unnecessary loss of marine life but also helps maintain healthy fisheries and protect the delicate balance of marine ecosystems. Additionally, the initiative raises awareness about the impacts of ghost gear and works toward innovative solutions, such as recycling and repurposing the retrieved gear, to further reduce its negative effects on the environment and marine biodiversity. Through these concerted efforts, the Global Ghost Gear Initiative contributes significantly to the broader goal of minimizing bycatch and promoting sustainable fishing worldwide.
Waterhaul is a company that is turning ghost nets found on the shores of the UK into sunglasses, eyewear and litter pickers.
Learn More
You can read more about the ghost gear issues raised above in the links below:
New Link in the Food Chain? Marine Plastic Pollution and Seafood Safety
2) Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic
3) Plastic Pollution - Our World in Data
4) http://www.fao.org/fileadmin/user_upload/newsroom/docs/Ghost_fishing_report.pdf
5) Ingested plastic transfers hazardous chemicals to fish and induces hepatic stress
https://www.nature.com/articles/srep03263
6) Marine Plastic Pollution: Sources, Impacts, and Policy Issues
https://www.journals.uchicago.edu/doi/10.1093/reep/rez012
7) http://www.unesco.org/new/en/natural-sciences/ioc-oceans/focus-areas/rio-20-
ocean/blueprint-for-the-future-we-want/marine-pollution/facts-and-figures-on-marinepollution/
8) https://www.sciencedirect.com/science/article/pii/S0269749121006904
9) Plastic waste associated with disease on coral reefs
https://science.sciencemag.org/content/359/6374/460.full
10) Millimeter-Sized Marine Plastics: A New Pelagic Habitat for Microorganisms and
Invertebrates
11) https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1442-8903.2010.00525.x
12) Assessing the Economic Benefits of Reductions in Marine Debris at Southern California
Beaches: A Random Utility Travel Cost Model
https://www.journals.uchicago.edu/doi/abs/10.1086/697152
13) https://www.sciencedirect.com/science/article/pii/S0025326X09004573
14) http://www.fao.org/responsible-fishing/marking-of-fishing-gear/voluntaryguidelines-
marking-fishing-gear/en/
15)
Reference for image: http://www.fao.org/responsible-fishing/marking-of-fishing-gear/
voluntary-guidelines-marking-fishing-gear/en/
Entanglement of Steller sea lions (Eumetopias jubatus) in marine debris: Identifying
causes and finding solutions
https://www.sciencedirect.com/science/article/pii/S0025326X09002264